The three-dimension CAD model is firstly cut into a series of two-dimension laminar flat sheets. Then these laminar flat sheets will be processed by AM equipment, and simultaneously be piled up layer by layer. Finally, the required three-dimension parts will be manufactured as roughly shown in the below figure:

The main technologies of 3D printing as follows:

1）Spraying Forming: Similar to the ink-jet printer, it selectively sprays liquid molding materials from the jet nozzle, and piles them up layer by layer to three-dimension structure.

2）Spraying Molding with Adhesive: A slight layer of powder materials is laid first, and then the adhesives should be sprayed out selectively through nozzle on the materials, and the powder materials will be bonded layer by layer to form a physical layer until three-dimension parts are formed.

3）Photosensitive Polymer Curing: The pre-configured liquid photosensitive polymer is scanned by a sort of light source, and then is solidified quickly.

4）Material Extrusion Molding: Filamentous polymer materials, under certain pressure, will pile up to three-dimension structure through melting from dot, line and surface after being softened by heating nozzle. During its molding, working platform should be moved down or the nozzle should be moved up. The above process is known as Fuse Deposit Manufacturing (FDM).

5）Laser Powder Sintering Molding: Its fundamental is similar to spraying molding with adhesive. The difference between them is that, in Laser Powder Sintering Molding, the powder material is bonded or fused together by heat energy other than glue to form the required shape.

6）Directed Energy Deposition Molding: It is equivalent to multi-layer laser cladding. Materials are fused while they are outputted from nozzle with laser or other sources, and these materials will be formed to physical layer after solidification, and then are accumulated layer by layer until three-dimension physical parts are formed.